1. Field of the Invention
The present invention relates to a surface mount lateral light emitting apparatus (side-view type light emitting apparatus) which is used for, for example, alighting apparatus, a display, a backlight of a cellular phone, a video auxiliary light source, and other general consumer light sources, and a fabrication method of the surface mount lateral light emitting apparatus.
2. Description of Related Art
A surface mount lateral light emitting apparatus which usually uses, for example, a light emitting diode (LED) is small and excellent in power efficiency, and emits a brilliant color. In addition, since the light emitting device is a semiconductor device, there is no concern about a blowout of the device. Further, the light emitting device is excellent in an initial drive performance and robust against vibrations and repeat of ON and OFF of the device. Since the light emitting device has the excellent characteristics described above, a light emitting apparatus using a light emitting device such as a LED and a laser diode (LD) has been utilized as various kinds of light sources.
The surface mount lateral light emitting apparatus includes a light emitting device, a mounting lead frame for mounting the light emitting device, a connecting lead frame to be connected to the light emitting device through a lead wire, a resin molding body (first resin molding body) covering most of each lead frame, and a translucent encapsulation resin (second resin molding body) for covering the light emitting device. This is disclosed in, for example, Japanese Patent Laid-open Publication No. 2005-259972. A concave housing portion is disposed on a light emitting surface formed on the first resin molding body, and the light emitting device is mounted on the mounting lead frame arranged in the concave housing portion. A translucent encapsulation resin, in which a fluorescent material is dispersed, is filled in the concave housing portion after an electrode of the light emitting device is connected to the connecting lead frame through the lead wire.
There are two types of surface mount light emitting apparatus, that is, a surface light emitting type (top-view type) and a lateral light emitting type (side-view type).
A constitution of the side-view type light emitting apparatus is basically identical to that of the top-view type light emitting apparatus except for arrangements of lead frames. A lead frame which is electrically connected to the light emitting device and projected outside the package is bended so that an end of the lead frame is on a plane identical to the package side face, which is parallel to an outgoing direction of the light.
It is noted that the side-view type light emitting apparatus is required to be ON at all times and has a stable light intensity since the apparatus is used for a backlight of a notebook PC.
Generally, a major molding method of a resin molding body which provides a less expensive high power surface mount light emitting apparatus has been injection molding of a thermoplastic resin because of its high productivity and thermoplastic property. The side-view type light emitting apparatus has also been molded by a similar manner. This is disclosed in, for example, Japanese Patent Laid-open Publication No. H11-45958 (see FIG. 5).
In the side-view type light emitting apparatus, when a width of a periphery portion of the concave portion is made thinner, a molding of the resin molding body by the injection molding using the thermoplastic resin has been difficult due to a low fluidity of the thermoplastic resin. In addition, when a temperature of the molding is increased for improving the fluidity of the thermoplastic resin, a trouble that a die can not be released from the resin has happened.
Considering the trouble described above, a technology which uses a thermosetting resin instead of the thermoplastic resin for the resin molding body has been developed. This is disclosed in, for example, the Japanese Patent Laid-open Publication No. 2005-259972.
It is noted that when the resin molding body is mass-produced by the injection molding, conventionally, the resin is filled and injected in a first die of a plurality of dies which are arranged in series, and the resin is sequentially filled in the adjacent die. In the resin molding body of the side-view type light emitting apparatus, a portion where the resin is filled and injected is the periphery portion of the concave portion. This is disclosed in, for example, the Japanese Patent Laid-open Publication No. H11-45958.
However, in recent years, a notebook PC is required more reduction in size, weight, and cost. Therefore, a light emitting apparatus to be installed in the notebook PC is also required reduction in size, weight, and cost.
In addition, since the die is released from the resin by pushing a portion where the resin is filled and injected after the injected thermoplastic resin is hardened, the resin molding body is required to have a strength resistant to the pushing. Therefore, there has been a limitation for thinning a width of the periphery portion of the concave portion. Specifically, if the width of the periphery portion of the concave portion is too thinned, a light from a light emitting device entirely passes through the periphery portion, thereby resulting in lowering of light extraction efficiency on a light emitting surface. On the other hand, if the thin periphery portion of the concave portion contains too much a light diffusion agent for increasing the light extraction efficiency on the light emitting surface, a fluidity of the thermoplastic resin forming the thin periphery portion is reduced, thereby resulting in difficulty in molding a thin periphery portion of the concave portion.
In addition, even if the thermoplastic resin is merely replaced by a thermosetting resin, a molding of the thin periphery portion (after hardening of the resin) of the concave portion in the side-view type light emitting apparatus and a molding of a complex shape posed by thinning the apparatus are difficult. Therefore, it has been required to select, for example, a proper thermoplastic resin and process.
It is, therefore, an object of the present invention to provide a small, light, and less expensive side-view type light emitting apparatus and a fabrication method of the apparatus.